The present invention relates to derivatives of cephalosporanic acid and to pharmaceutical compositions comprising thereof. More in detail, the present invention relates to a series of antibiotics which have been prepared by chemically modifying a substituted cephalosporanic acid having antibacterial activity, and pharmaceutical compositions comprising at least one of the series of the chemically modified, substituted cephalosporanic acid.
The chemically modified, substituted cephalosporanic acid according to the present invention itself has no antibacterial activity, however, after having been absorbed in living body of the host, the anti-bacterial activity is specifically regained
In general, antibiotics related to cephalosporins are now broadly used and show a considerably favorable selectivity against bacteria, however, because of the anti-bacterial activity also against the bacterial colonies habitually present in living body, particularly those in the intestines of the host, such antibiotics have a demerit of disturbing the intestinal useful bacterial colonies, particularly when such an antibiotic is orally administered. Such a situation causes the so-called microbisme selectionne et substitue resulting, on some cases, in colitis and diarrhea.
The present inventors have found, as a result of studies in antibiotics without having such a demerit, that the derivatives of a substituted cephalosporanic acid, represented by the following formula (I) are effective in the above-mentioned sense, and have attained the present invention.
Accordingly, the object of the present invention is to provide the derivatives of a substituted cephalosporanic acid, which are useful as the active ingredient of antibiotic composition and do not disturb the intestinal bacterial colonies in the host.